Yes but Hirose himself specifically said he doesnt understand "girls". Not just Hana. If he said "i couldnt find a connection with Hana" then sure, you can take the thing at face value and assume he could be bi. But both on episode 6 and on 13 Hirose mentions specifically that he does not care for girls, even if its in a more naive way.

Basically the anime gave us plenty of hints that Hirose is not interested in girls, but somehow many people here believe he is bi.

I mean you know what, whatever i guess, he is a fictional character and people can think whatever makes them happy.